1. Field of the Invention
The present invention relates to a sheet processing apparatus and an image forming apparatus incorporating a sheet processing apparatus.
2. Description of the Related Art
There has conventionally been a copying apparatus equipped with modes, such as a cover sheet mode and an identification sheet mode, in which a type of sheet (hereinafter referred to as a xe2x80x9cspecial sheetxe2x80x9d) different from a regular recording sheet can be inserted as a first or last page or inserted anywhere among the pages. A user sets these modes through a control panel of the copying apparatus to enable, for example, a sheet of a different color to be inserted as a cover sheet or as a separating sheet.
As a method for supplying a special sheet, there has been proposed the method in which a special cassette provided in a main unit of a copying apparatus supplies the special sheet, or a method in which a sheet feeder for supplying a special sheet is provided in a sheet processing device, such as a finisher, so as to supply the special sheet from the sheet feeder. There has been also proposed to provide the capability of stapling or punching special sheets conveyed from the sheet feeder.
However, no satisfactory corrective measures have been taken for skewing of special sheets conveyed from a sheet feeder or a special cassette or the like. Hence, if a special sheet is conveyed in a skewed state from the sheet feeder or the special cassette or the like mentioned above, then a paper jam may occur during conveyance and, even without a paper jam, an inconvenience, such as a failure of punching or the like at a desired position of a sheet may occur. This causes a user a problem in which the user has to prepare another sheet of the same type, involving extra efforts and labor for the user, in addition to increased cost.
Accordingly, the present invention has been made with a view toward overcoming the shortcomings described above, and it is an object thereof to provide a sheet processing apparatus and control method, an image forming apparatus, and a storage medium.
To this end, according to the present invention, there is provided a sheet processing apparatus and control method, an image forming apparatus, and a storage medium that are able to prevent causing a user extra time and efforts and extra cost even if a sheet skews.
In accordance with these objects, there is provided a sheet processing apparatus comprising a first stacking tray connectable to an image forming apparatus and on which sheets are stacked, conveying means for conveying a sheet loaded on the first stacking tray and a sheet on which an image has been formed by the image forming apparatus, and a second stacking tray for stacking the sheets conveyed from the first stacking tray and the sheet on which an image has been formed by the image forming apparatus. Sheet processing is performed on the sheet conveyed by the conveying means from the first stacking tray, according to an operation mode of the image forming apparatus, the sheet processing apparatus comprising, detecting means for detecting a skew amount of a sheet conveyed from the first stacking tray, determining means for determining whether to perform sheet processing by the sheet processing apparatus, and control means for controlling conveyance of the sheet by the conveying means based on a skew amount of the sheet detected by the detecting means and a determination result of the determining means.
In accordance with another aspect of the present invention, there is provided a sheet processing apparatus for implementing sheet processing on a sheet, comprising, conveying means for conveying a sheet for processing, and control means for inhibiting operation of the conveying means based on a skew amount of the sheet conveyed by the conveying means. The control means permits the operation of the conveying means if the skew amount of the sheet conveyed by the conveying means is a skew amount lower than an amount that will cause sheet conveyance failure, and the control means inhibits the operation of the conveying means if the sheet is a sheet for a job involving sheet processing, and permits the operation of the conveying means if the sheet is a sheet for a job in which sheet processing is not performed when the skew amount of the sheet conveyed by the conveying means is the skew amount lower than the amount that will cause sheet conveyance failure.
In accordance with yet other aspects of the present invention, there are provided methods for carrying out the above sheet processing, as well as computer readable storage medium for storing programs for controlling the above apparatus.
Further objects, features and advantages of the present invention will be better understood from the following description taken in connection with the accompanying drawings.